Engine piston and method of making the same



Aug. 14, 192:3. Y F. L. MADLER ENGINE PISTON AND METHOD OF MAKING THE SAME Filed April 6. 1921 W/Ynasses Jn Mental":

Fatented Aug. I4 11%23.

err ears wanna tours Lam. or oror'rnneune, GERMANY.

ENGINE PISTON AND METHOD OT MAKING E SAME.

Application filed April 6, 1921. Serial No. 459,194.

(GRANTED un'nna' r rnovrsrons or rm: ACT or MARCH 3, 1921, i1 STAT. n, 1313.

To all whom it may concern:

Be it known that I, FRANZ L. MKDLER, a citizen of the German Empire, residing at Charlottenburg, Germany, have invented it certain new and useful Improvements in Enine Pistons and Method of Making the ame (for which I have filed ap lication in Germany, February 13, 1919, atent No. 358,074, dated June 6, 1922), of which the no following is a specification.

My invention refers to engine pistons and more especially to a method of manufacturing light metal pistons reinforced with hard metals, for use in internal combustion en- 15 gines. Up till now such pistons have been made by insertin reinforcing rings in the moulds in which the aluminum piston is cast. In cooling down from the casting temperature to the temperature under working conditions the above rings contract in such a" manner that intervening spaces are produced between the rings and the body of the piston, disturbances in the transmission of heat from the rings to the body of the piston being the consequence, whereby the advantages gained by employing a light metal with a good coeflicient of heat, are partly neutralized.

According to thepresent invention, the piston and the reinforcing rings or shell are joined together at a temperature almost corresponding to the working temperature, and this in such a manner that the semifinished body of the piston is rigidly connected, either entirely or partly, with a shell of hard metal, whereafter it is subjected to the finishing work. Preferably the annular shell of hard metal is further fixed on the piston body by rolling in annular grooves.

In the drawings afiixed to this specification and forming part thereof a piston according to the present invention is shown by way of example in cross-section.

Referring to the drawings, the body aof the piston is made of aluminum or some other light metal or alloy with the usual transverse wrist-pin apertures and its exterior surface is provided with grooves 72. The shell e of steel or bronze provided with grooves for the insertion of the piston rings, is fixed at one end of the aluminum body by pressing. The other or free portion of the body a serving to guide the piston, is fitted with the closely fitting shell a as-already described, by first heating the body a and sleeves a toabout 220 C. and then slippingthe heated sleeve 0 on to the body at, until the forward end of the sleeve 0 is approximately in tangential registry with the wrist-pm aperture. It is preferred that more than one of the sleeves c be employed and that such sleevesbe spaced apart from each other as shown in the drawing, whereby buckling is prevented due to the fact that the di mensions of each individual sleeve-are kept within limits where buckling cannot occur.

The metal of which the sleeves c is comthe body a as described, annular grooves d are rolled into the sleeves at the points of the body a corresponding to the grooves b thereon, said grooves 03 being, as illustrated,

of shape and dimensions such as to serve aslubricant containers. In this manner the body of the piston is enclosed on all sides in a shell of metal which is firmly secured against shifting and which speedily conducts the heat generated by the gases of combustion. The annular rooves d serve to carry along and collect the lubricant and the space between adjacent sleeves 0 .may readily be dimensioned, as shown in the drawing, so that it may serve a similar purose.

It will be understood that the shells or sleeves e may be initially formed in any suitable or preferred manner and that the scope of the claims generally, is intended to embrace equivalents.

I claim:

1. The method of making pistons which conslsts in placing on a semi-finished light metal piston body a closely fitting metal sleeve, both heated at the time of their assembly-to a temperature approaching the working temperature of the piston and then finishing the combined piston and sleeve by interposing between the said two elements means to prevent axial movement of one with respect to the other.

2. The method of making pistons which consists in providing'grooves upon the exterior surface of a semi-finished light metal piston body, then placing upon said bodya 'closelyfittin metal-sleeve, both heated at the'time of t ieir assembly to a temperature approaching the Working temperature of the piston and then, by rolling, forming annular grooves upon the sleeve at those parts thereof corresponding to the grooves in the piston body.

3. The method of making pistons which consist in providing. grooves upon the exterior surface of a'semi-finished light metal piston body, then placing upon said body a closely fitting metal sleeve, both heated at the time of their assembly to a tei nperature approaching the working temperature of the piston and'then, by rolling, forming annular grooves of lubricant carrying capacity and dimensions upon the sleeve at those parts thereof corresponding to the grooves in the piston body.

4. The method of making pistons which consists in placing on a semi-finished light metal piston body, a plurality of closely fitting metal sleeves, the edges of adjacent sleeves being close together but out of contact with each other, heating the piston and sleeves at the time of their assembly to a temperature approaching the working temperature of the piston and then interposing between the piston body and each of these sleeves means to prevent axial'movement of one With respect to the other.

5. The method of making pistons which consistsin providing grooves upon the ex terior surface of a semi-finished light metal piston body, then placing upon said body a plurality of closely fitting metal sleeves, the edges of adjacent sleeves being close together but out of contact with each other, heating the piston and sleeves at the time of their assembly to a temperature approaching the working temperatureof the piston and then by rolling, forming annular grooves upon each of the sleeves at those parts thereof corresponding to the grooves in the piston body.

6. The method of making pistons which consists in placing on a semi-finished light metal piston body, means to carry piston rings and then covering practically the entire remaining surface of the piston body from the other end thereof up to the im mediate vicinity of the recessed pin apertures of said body With a closely fitting casing of metal, heating the metal constituting wrist-pin apertures, means at one end of the body adapted to accommodate piston rings, grooves extending circumferentially around the other end of said body and means at said end of said body adapted to slide smoothly over the inner walls of a piston cylinder, said means comprising an annular metallic member'whose entire inner surface is in close and intimate contact at all points with the corresponding outer surface of the piston body, one edge of said member being closely ad acent to the wrist-pin apertures of the piston body and grooves circumferentially located upon said member at the points corresponding to the grooves in the piston body and of lubricant-carrying capacity and dimensions, the metal displaced by the formation of said grooves being driven into the grooves on-the piston and serving to firmly hold the sleeve and the piston against relative axial displacement.

8. A piston comprising a light metal body, wrist-pin apertures, means at one end of the body adapted to accommodate piston rings, grooves extending cireumferentially around the otherend of said body and means at said end of said body adapted to slide smoothly over the inner walls of a piston cylinder, said means comprising a plurality of annular metallic members whose entire mner surface 1s in close and intimate condimensions, the metal displaced by the formation of said grooves being driven into i the grooves on the piston and serving to firmly hold the sleeve and the piston against relative axial displacement.

In testimony whereof I afiix my signature.

FRANZ LOUIS MADLER. 

